A good boiler for constant circulation

vvzz

Hi All,
I just purchased a 3 story mansard house in Boston area. It is currently a 3 family, but I will be converting it back to its original single family state(luckily nothing was really altered, I just need to demo 2 kitchens) Since it's a 3 family, it has three separate boilers(newish direct vent Burnhams) with baseboard heat.
I dislike baseboards (almost as much as forced air) and given that I have successfully converted my other house back to CI radiators(with full ODR via injection), I plan to do the same in this house. The radiation will be a mix of CI radiators that I already started to procure and some radiant as I get to remodel kitchen and bathrooms. Since it will all be designed from scratch, I will hopefully be able to match the size of the rads to run them at the same temperature as flooring. Or maybe I will mix down, I haven't decided yet.

I'm planning on doing a constant circulation system without zones with TRVs on all radiators(works awesomely in my other house)

So the big question is, which NG boiler should I pick? I'm looking for something that has controls receptive to constant circulation(i.e. without boost functionality or the like) I'm currently leaning towards Triangle Tube Prestige - the trimax control seems to be a good fit and Triangle Tube boilers seem to get good reviews. Is there any other boiler I should consider?

Robert O'Brien

That or a Viessmann Vitodens 200 would be my choices

Ironman

Just about any mod/con will work just fine. If it has a boost function, that can be disabled at the control.

I personally prefer ones that have a fire tube HXs like the TT, Lochinvar WHN, etc. The ECR laser tube is a good boiler. The Bosch GreenStar has the best intuitive control in the FW 200 that works extremely well with constant circ as it can actually determine how many btus are needed over a period of about three weeks.

Make sure that a detailed heat loss calc is done to determine the proper sizing of rads, piping, pumps, boiler, etc. It will also be the basis for determining water temps, ODR settings, etc.

Paul Pollets

I prefer the Viessmann Vitodens 200 B2HA. The control is extremely easy to program and the boiler can provide up to 3 mixed temps + the indirect DHWT. The appliance is well represented in the Boston area.

vvzz

Great! Thanks for all the answers. I have already done a heatloss calculation. The house is right around 100k BTU/hr, but I added quite a padding with high infiltration input. As I rehab the windows and address other leaks, it should be a perfect match for Triangle Tube PTE100.

Does anyone have anything good/bad to say about the in-cabinet indirect in the Prestige package? I really like the idea of not having a separate tank.

SWEI

vvzz said:

Does anyone have anything good/bad to say about the in-cabinet indirect in the Prestige package?

IME it is too small for any house that needs ~100,000 BTU/hr to heat it.

Rich_49

Have a look at these . The combi is a monster and I hate combis .
http://www.htproducts.com/EFT_Combination_Floor.html

Really good option for constant and the price point is killer , low maintenance , air and dirt separation built in , low head loss , no P/S required .

http://www.htproducts.com/pioneer.html

Local products as far as you're concerned

vvzz

SWEI said:

IME it is too small for any house that needs ~100,000 BTU/hr to heat it.

Hmm... It's only three of us and TT claims 180 Gal first hour rating at 70 degree rise. Even if it delivers half of the claimed number, it still seems pretty good. Or are you thinking that there won't be enough output for both heat and water on a design day?

Also, today I decided to see how much radiation I will need for each room, and came to realization that if I were to size radiators based on 140 top temp, that will probably be a little bit too many radiators(front parlor is 10k BTU loss alone and I'm not keen on blown in insulation in historic buildings) So I might need to run them a little hotter(160) and mix down for radiant floor. But trimax control doesn't seem to support controlling a mix valve.

So I started considering Vitodens 200, but Viessmann doesn't sell to consumers.

Lochinvar was also mentioned here and now I'm considering that. It still requires a separate mixing addon, but at least it exists. Not to mention a separate indirect tank.

Rich_49

180 GPH is only 3 GPM . Do the math .

SWEI

100,000 BTU/hr loads usually go with 5,000+ square foot houses. 5,000+ square foot houses typically have large DHW demands.

What did your heat loss calc actually come in at, and how many ACH's were assumed?